Several laparoscopic procedures require the bulk removal of body tissue or organs through a limited surgical opening. As such, the tissue needs to be morcellated within the body cavity into smaller pieces of tissue from where they can be removed with laparoscopic graspers or tenaculums through minimally invasive access ports or the morcellation tool itself. Examples of such tissue morcellation are found in laparoscopic nephrectomies, splenectomies, or laparoscopic supracervical hysterectomies.
In all laparoscopic cases for bulk removal of entire organs, it is advantageous to morcellate the tissue into large tissue segments, rather than small tissue breakups, which then can be removed in very few extraction steps. Apart from time savings, the removal of large tissue segments, rather than small tissue chips, also reduces the chance of cross-contamination with malignant or cancerous tissue. Specifically for the example of laparoscopic supracervical hysterectomies, it is advantageous to morcellate the severed uterus along the surface of the fundus (generating a continuous tissue peel), rather than to repetitively core into the bulk of the uterus (generating a multitude of tissue chips).
To accomplish laparoscopic tissue morcellation and extraction, the tissue is usually first seized with a grasper or tenaculum that is inserted into the abdomen through the inner lumen of the morcellator shaft. In order to maintain pneunoperitoneum, the grasper or tenaculum is sealed against the morcellator shaft by a duck bill valve or floating seal arrangement. After engaging a motor/drive mechanism to cause rotation of the hollow, cylindrical cutting tube, the tissue is continuously cut as it is pulled into the morcellator shaft. As a result, either small tissue fragments or rather large tissue peels can be removed from the abdomen through the morcellation tool.
Ideally, the tissue or organ is simultaneously manipulated with a second set of laparoscopic tools so as to place the tissue in a favorable position in respect to the tissue morcellator. In the case of morcellation and removal of uteri in laparoscopic hysterectomies, for example, it is advantageous to manipulate the severed uterus in a rotating fashion in respect to the morcellator. This allows “peeling” of the fundus in a continuous tissue strip while simultaneously removing it out of the body cavity.
Although morcellators based on cylindrically rotating cutting tubes enable much faster and more practical tissue removal than tissue “chipping” devices, they do show some practical and functional disadvantages.
One drawback is that the tissue cannot be visualized as it is being pulled into the morcellator. When tissue or bits of tissue are pulled through the morcellator during cutting and extraction, small pieces of tissue can be left within the shaft or seal portion of the device. These pieces might be pushed back into the abdomen without being noticed when an instrument is inserted.
Another disadvantage of this arrangement is that both the shaft and the opened jaws of the grasper or tenaculum may damage the edge of the cylindrical cutting blade during manipulation, dramatically reducing its effectiveness and life.
A functional disadvantage of the rotating cylindrical cutting tube design is that tissue can rotate along the longitudinal axis of the cylindrical cutting tube. This is especially the case if the tissue is in contact with the inner lumen of the rotating cutting tube, and is pronounced for rather small-sized and light tissue sections. An arrangement of stationary inner sleeve tubes remedy this problem only partially if the tissue still has contact with a section of the cutting cylinder.
Another practical disadvantage of current cutting tube arrangements in terms of continuous tissue removal is that tissue being fed into the morcellator in a rotating fashion, which allows peeling of the tissue, can overspill beyond the opening of the morcellator. This prevents the remaining bulk tissue from being further rotated into the opening of the morcellator, and interrupts the continuous peel.